In certain medical procedures, a patient is located in a supine position on a table or the like with one of a variety of imaging or radiographic techniques being used to provide an instantaneous or continuing representation of the patient's condition or response to the procedure. Often such procedures are directed toward the patient's coronary system and require accurate imaging of the chest cavity, particularly around the heart.
Furthermore, in order to obtain an accurate or more complete representation of the patient's condition, it is necessary to carry out the imaging techniques along a variety of axes in order to provide a more accurate or complete representation of a three-dimensional nature.
In particular, the present invention contemplates medical procedures having the object of reducing or eliminating blockage in the coronary system, especially adjacent the heart. The earliest of these procedures, and that used most commonly in the past, was the coronary bypass involving the use of surgical techniques for treating or removing the cause of blockage.
More recently, relatively non-surgical techniques have been developed for this purpose and are commonly used instead of coronary bypass surgery where possible. One such technique involves angioplasty procedures wherein a balloon catheter is introduced into the coronary arteries. This procedure is particularly effective for treating coronary blockage caused by localized deposits of plaque on the walls of the coronary vessels. The balloon catheter is caused to move through the coronary vessel until it is aligned within the constriction caused by the plaque. The balloon catheter is then expanded to form an enlarged passage through the vessel by causing the plaque to be adhered to the vessel wall.
Numerous variations of such angioplasty techniques are well known to those skilled in the art and do not require further discussion to permit a complete understanding of the present invention. However, it is noted that angioplasty, including newly developed laser angioplasty, may be either brachial or femoral in nature. That is, the catheter is introduced into the coronary system through an incision in the arm in brachial angioplasty or in the leg in femoral angioplasty.
In all such angioplasty techniques as well as in bypass surgery itself, very accurate radiographic imaging is necessary in order to properly observe the lesion or blockage in the coronary system and the effect of the treatment. Such an image or angiogram is obtained as a precursor to bypass surgery for diagnostic purposes. Similarly, angiographic procedures may be employed before, during and after angioplasty procedures to diagnose the initial condition of the patient and to monitor the effect of the procedure on the patient. Normally, the patient is arranged in a supine position on a supporting table or the like, imaging being carried out by a C-arm adapted to rotate about the patient so that the coronary system may be viewed from all angles.
Because of the relatively massive size of such imaging equipment, the area in which the patient is located within the rotating C-arm is quite limited. Furthermore, provision is normally made for immobilizing the patient's right arm during imaging, both to prevent the arm from interfering with the obtaining of clear images of the coronary system and also to maintain the patient in a fixed position while a number of images are obtained. In the past, the patient's right arm was arranged on rigid arm boards extending laterally from the side of the table supporting the patient.
With the patient in this position, it has been relatively easy in the past to obtain anterior-posterior or vertical views of the coronary system and even slightly angulated views with the C-arm rotated to permit imaging along a plane inclined from vertical. However, fully angulated or lateral imaging has presented difficulties for a number of reasons. Initially the laterally extending arm boards often physically interfere with the C-arm because of the relatively limited space provided for the patient and supporting table. Furthermore, with the arm boards extending laterally from the table, the patient's right arm tends to be positioned in or near the plane of the patient's heart which, as noted above, is the area of prime interest in such angiographic techniques.
Thus, both the patient's arm and the arm board tend to detract from fully angulated or lateral images since they are at least somewhat radiopaque and tend to cast shadows in the angiograms.
This difficulty in obtaining angulated angiograms naturally tends to interfere with the proper diagnosis and treatment of the patient by angioplasty techniques as well as with bypass surgery and the like where accurate and multiangled images are required.
Accordingly, there has been found a need for improved apparatus for facilitating angulated imaging of the coronary system of supine patients arranged on a supporting table or the like. In perfecting the present invention, it was initially discovered that prior restraints such as arm boards used in these procedures were undesirable for at least two reasons. Initially, the arm boards extended laterally from the table supporting the patient so that the arm boards as well as the patient's arm located on the arm boards tended to physically interfere with necessary rotation or positioning of the imaging equipment. Furthermore, both the patient's arms and the arm boards often prevented the obtaining of precise angulated images because of their relatively radiopaque nature and the position of the patient's arm generally in the plane of the heart.